EP0089687A2 - Méthode et dispositif électronique pour la détection du décrochage du combiné téléphonique en présence du courant d'appel - Google Patents

Méthode et dispositif électronique pour la détection du décrochage du combiné téléphonique en présence du courant d'appel Download PDF

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Publication number
EP0089687A2
EP0089687A2 EP83102858A EP83102858A EP0089687A2 EP 0089687 A2 EP0089687 A2 EP 0089687A2 EP 83102858 A EP83102858 A EP 83102858A EP 83102858 A EP83102858 A EP 83102858A EP 0089687 A2 EP0089687 A2 EP 0089687A2
Authority
EP
European Patent Office
Prior art keywords
current
signal
ringing
circuit
wire
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP83102858A
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German (de)
English (en)
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EP0089687B1 (fr
EP0089687A3 (en
Inventor
Flavio Melindo
Mario Sartori
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Telecom Italia SpA
Original Assignee
CSELT Centro Studi e Laboratori Telecomunicazioni SpA
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Application filed by CSELT Centro Studi e Laboratori Telecomunicazioni SpA filed Critical CSELT Centro Studi e Laboratori Telecomunicazioni SpA
Publication of EP0089687A2 publication Critical patent/EP0089687A2/fr
Publication of EP0089687A3 publication Critical patent/EP0089687A3/en
Application granted granted Critical
Publication of EP0089687B1 publication Critical patent/EP0089687B1/fr
Expired legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M19/00—Current supply arrangements for telephone systems
    • H04M19/02—Current supply arrangements for telephone systems providing ringing current or supervisory tones, e.g. dialling tone or busy tone
    • H04M19/026—Arrangements for interrupting the ringing current

Definitions

  • the present invention relates to subscriber telephone signalling and in particular it concerns an electronic circuit for detecting the lifting of the telephone handset in presence of ringing current.
  • the call is effected by means of a low-frequency (as a rule 25 Hz) high-voltage (typically 70 Veff) signal.
  • the ringing-current is emitted in series with the battery voltage, so that if the handset is on hook, there is only alternating current flow, while the d. c. component is blocked by the capacitor connected in series with the ringer.
  • the methods generally used in this case are two.
  • the most immediate method uses a low-pass filter with a cut-off frequency of a few Hertz to separate the two components; yet it has the disadvantage of requiring capacitors of very high value and of presenting a long response time.
  • it is ill-suited to be implemented with an integrated circuit.
  • the second method is based on the fact that the presence of a d. c. component changes the ratio between positive and negative half-periods of the ringing current; said ratio can be computed by means of digital circuits, such as those described for instance in the Patent Application No. 67252-A/80, filed in Italy in the name of CSELT, on the 19 February 1980 and corresponding to European Patent Application No. 81100995. 0, published on the 26th August 1981.
  • the electronic circuit provided by the present invention which is apt to detect the lifting of the handset in presence of ringing current.
  • Said circuit allows the flow of d. c. current through the line loop to be detected in presence of considerably higher a. c. current, it is easy to integrate and requires a single external capacitor of low value.
  • the main object of the present invention is to provide a method of detecting the lifting of the telephone handset in presence of ringing-current flow through the line loop, characterized in that a multiplication of the line current is effected both by a constant value and by a chopping signal consisting of a train of pulses with a convenient ratio between duration and period, the resulting signal undergoes an integrating operation over one or more complete periods of the ringing current, and it is compared with a voltage threshold in order to detect the presence of d. c. current flow through the line.
  • CC is an ordinary circuit apt to generate at the output, connected to wire 5, a pulse in correspondence with each leading edge of the signal supplied by Cl.
  • GD is a circuit which controls the charging current of a capacitor C proportionally to the line current flowing through a wire 3, under the control of the commands received from circuit CC and of a chopping signal, with constant period, received via wire 7.
  • C2 is a circuit which compares the voltage across capacitor C with suitable threshold voltages applied to the inputs connected to wires 4' and 4", when enabled by the signal supplied by CC on wire 5.
  • circuit CC At the beginning of a ringing-voltage period, identified by a leading edge of the signal at the output of Cl, circuit CC generates a pulse which through GD discharges capacitor C. From that instant the voltage across the capacitor is determined by the current supplied by circuit GD, and hence it is proportional to the integral of the current flowing through the line. At the end of a period T of the ringing voltage (or as an alternative after an integer number n of periods) voltage Vc across the capacitor results to be proportional to the only d. c. component of such current.
  • the leading edge of the pulse supplied by CC enables the operation of voltage comparator C2, by which it can be determined whether the d. c. component exceeds or not the pre- determined threshold and it can be recognized the off-hook condition, supplying a suitable signal on wire 6. Immediately afterwards the next detection cycle begins.
  • the ringing current emission is automatically interrupted at local level, waiting for a certain acknowledgement of the occurred lifting by the circuits of the line unit entrusted with it. If such an acknowledgment does not arrive within a predetermined time period, the call is reattempted, as in this case it can be supposed that the detection has erroneously occurred owing to line noises.
  • Circuit GD can be a normal current mirror with output/ input ratio equal to Kl. However, if practical-value capacitors and voltage in a range of a few volts are used, coefficient K1 gets too small. By way of example, a ratio Kl equal to 1:400, which is difficult to implement with integrated technology, would be necessary to obtain an integration voltage Vc of 1 V at a current Idc of 10 mA with a period T of 40 ms and a capacitance c of 1 / u.F.
  • K2 can easily attain the value of many tens, also Kl can be increased by the same value.
  • a possible circuit GD, together with capacitor C, is depicted in the circuit diagram of Fig. 2.
  • coming via wire 3 from sensors placed out of the circuit itself, drives a current mirror circuit Sl, which generates in turn three equal currents flowing in wires 20, 21, 22.
  • This signal is used as a clock signal for a flip-flop MT, the true output of which, connected to wire 23, passes therefore from a logic level to the other at each zero-crossing of current in wire 20.
  • the complemented output is connected to wire 24.
  • Circuit S3 drives in turn S4 and therefore, depending on the state of flip-flop MT, either the current furnished by S2 or drawn by S4 flows through wire 2, and, as a consequence, capacitor C is traversed by a positive or negative current.
  • Gates A1 and A2 can be inhibited by the chopping signal present on 7 and, as a consequence, current flowing through capacitor C can be annulled; such signal, supplied from the outside, represents the constant K2, being characterized by a period Tc and by pulses with a time duration Ta.
  • the channel syn- nism signal generally presented in a PCM codec, i.e. a coder-decoder for coding and decoding speech signals as known e.g. from IEEE Journal of Solid-State Circuits, Vol.SC-16, No.4, August 1981, pages 308-314, (3,9 ⁇ s/ 125 ⁇ s) of digital switching means, could be conveniently used to this aim.
  • PCM codec i.e. a coder-decoder for coding and decoding speech signals as known e.g. from IEEE Journal of Solid-State Circuits, Vol.SC-16, No.4, August 1981, pages 308-314, (3,9 ⁇ s/ 125 ⁇ s) of digital switching means, could be conveniently used to this aim.
  • the diode bridge consisting of Dl, D2, D3, D4 is driven through wires 25 and 26 by current mirror circuits S5 and S6.
  • S5 is driven through T5 by the signal supplied by circuit CC (Fig. 1) on wire 5 and drives circuit S6 via wire 27.
  • the pulse on wire 5 turns on the diodes and hence it causes C discharge.
  • the same pulse causes a current to flow through wire 28, at one of the outputs of S5, which inhibits through T3 gates Al and A2, thus blocking possible charging currents of C.
  • circuit CC apt to supply at the output a pulse per each leading edge of the ringing signal limited by C1, is depicted in Fig. 3.
  • the square-wave signal, received via wire 8, is sent to the serial input of a 5-stage shift register SR, while the clock signal is applied to wire 31.
  • the true output of the first stage and the one complemented by the last one are sent to an AND gate P, which supplies at the output on wire 5 the required pulse train.
  • the already-cited chopping signal can be used as a clock signal.
  • Voltage comparator C2 apt to compare the voltage amplitude across the capacitor with the pre-determined threshold voltages, can be implemented, by instance, according to the scheme shown in Fig. 4.
  • Two comparators CT1 and CT2 have an input connected to the capacitor, via wire 2, and the other via wires 4' and 4", connected to two threshold voltages with equal amplitude and opposite sign.
  • the outputs are connected in parallel and access via wire 40 the input of a flip-flop D, the clock input of which is connected to wire 5.
  • Waveform a) is present on wire 1 (Fig. 1), b) on wire 7, c) on wire 8, d) on wire 5, e) on wire 3, f) on wire 34 (Fig. 2), g) on wire 23.
  • the waveform of the current supplied by S2 is denoted by h), the current drawn by S4 by i), the voltage on wire 2 by 1), the voltage on wire 40 by m) and the voltage on wire 6 by n) (Fig. 4).
EP83102858A 1982-03-24 1983-03-22 Méthode et dispositif électronique pour la détection du décrochage du combiné téléphonique en présence du courant d'appel Expired EP0089687B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT6737182 1982-03-24
IT67371/82A IT1155661B (it) 1982-03-24 1982-03-24 Circuito elettronico per la rivelazione dello sgancio del microtelefono in presenza della corrente di chiamata

Publications (3)

Publication Number Publication Date
EP0089687A2 true EP0089687A2 (fr) 1983-09-28
EP0089687A3 EP0089687A3 (en) 1984-12-19
EP0089687B1 EP0089687B1 (fr) 1986-11-26

Family

ID=11301842

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83102858A Expired EP0089687B1 (fr) 1982-03-24 1983-03-22 Méthode et dispositif électronique pour la détection du décrochage du combiné téléphonique en présence du courant d'appel

Country Status (9)

Country Link
US (1) US4528425A (fr)
EP (1) EP0089687B1 (fr)
JP (1) JPS58207758A (fr)
BR (1) BR8301380A (fr)
CA (1) CA1194627A (fr)
DE (2) DE3367993D1 (fr)
DK (1) DK116083A (fr)
ES (1) ES8403001A1 (fr)
IT (1) IT1155661B (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2553893A1 (fr) * 1983-10-19 1985-04-26 Texas Instruments France Procede et dispositif de detection d'une transition de la composante continue d'un signal periodique, notamment pour joncteur telephonique
EP0143435A2 (fr) * 1983-11-23 1985-06-05 STMicroelectronics S.r.l. Circuits téléphoniques à intégration monolithique pour la détection d'arrêt d'appel
FR2575021A1 (fr) * 1984-12-18 1986-06-20 Thomson Csf Circuit d'interface d'abonne telephonique incorporant des moyens de detection de decrochage du combine en phase d'appel et procede de detection correspondant
WO1995020289A1 (fr) * 1994-01-21 1995-07-27 Telefonaktiebolaget Lm Ericsson Procede de detection de decrochage pendant la sonnerie d'appel et utilisation d'un circuit d'interface de ligne d'abonne pour detecter le decrochage pendant la sonnerie d'appel
EP0675629A1 (fr) * 1994-03-04 1995-10-04 Siemens Aktiengesellschaft Procédé pour la détection sûre de décrochage pendant l'alimentation d'un signal de sonnerie dans une centrale téléphonique numérique et circuit pour sa mise en oeuvre

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS633547A (ja) * 1986-06-23 1988-01-08 Nec Corp リングトリツプ検出回路
US7082106B2 (en) 1993-01-08 2006-07-25 Multi-Tech Systems, Inc. Computer-based multi-media communications system and method
US5682386A (en) 1994-04-19 1997-10-28 Multi-Tech Systems, Inc. Data/voice/fax compression multiplexer
US5757801A (en) 1994-04-19 1998-05-26 Multi-Tech Systems, Inc. Advanced priority statistical multiplexer
US5905794A (en) * 1996-10-15 1999-05-18 Multi-Tech Systems, Inc. Caller identification interface using line reversal detection
US6351533B1 (en) 1998-01-26 2002-02-26 Xircom, Inc. System and method for protecting devices connected to a telephone line
KR100666986B1 (ko) * 2004-11-12 2007-01-10 삼성전자주식회사 비접촉식 정전센서를 이용한 전화기

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2356325A1 (fr) * 1976-06-25 1978-01-20 Ibm Procede de controle de l'etat raccroche/decroche d'un combine telephonique connecte a un reseau telephonique et circuit en comportant application
DE2816981A1 (de) * 1977-04-28 1978-11-02 Ibm Einrichtung zur messung der gleichstromkomponente in einem ueberlagerten wechselspannungssignal
EP0034339A1 (fr) * 1980-02-19 1981-08-26 CSELT Centro Studi e Laboratori Telecomunicazioni S.p.A. Circuit téléphonique pour la détection de décrochage pendant la génération de la cadence d'appel

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5368010A (en) * 1976-11-29 1978-06-17 Nec Corp Ring trip circuit
FR2470498A1 (fr) * 1979-11-21 1981-05-29 Trt Telecom Radio Electr Dispositif de detection du bouclage d'une ligne d'abonne pendant la sonnerie
JPS5680952A (en) * 1979-12-05 1981-07-02 Nec Corp Subscriber monitoring circuit
US4396805A (en) * 1981-09-21 1983-08-02 Siemens Corporation Ring trip detector for a subscriber line interface circuit

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2356325A1 (fr) * 1976-06-25 1978-01-20 Ibm Procede de controle de l'etat raccroche/decroche d'un combine telephonique connecte a un reseau telephonique et circuit en comportant application
DE2816981A1 (de) * 1977-04-28 1978-11-02 Ibm Einrichtung zur messung der gleichstromkomponente in einem ueberlagerten wechselspannungssignal
EP0034339A1 (fr) * 1980-02-19 1981-08-26 CSELT Centro Studi e Laboratori Telecomunicazioni S.p.A. Circuit téléphonique pour la détection de décrochage pendant la génération de la cadence d'appel

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2553893A1 (fr) * 1983-10-19 1985-04-26 Texas Instruments France Procede et dispositif de detection d'une transition de la composante continue d'un signal periodique, notamment pour joncteur telephonique
EP0139594A1 (fr) * 1983-10-19 1985-05-02 TEXAS INSTRUMENTS FRANCE Société dite: Méthode et appareil pour la détection de la transition de la composante continue du courant d'un signal périodique, en particulier pour les circuits d'interface de boucle d'abonné
US4645881A (en) * 1983-10-19 1987-02-24 Texas Instruments Incorporated DC level trip detector
EP0143435A2 (fr) * 1983-11-23 1985-06-05 STMicroelectronics S.r.l. Circuits téléphoniques à intégration monolithique pour la détection d'arrêt d'appel
EP0143435A3 (en) * 1983-11-23 1987-06-16 Sgs-Ates Componenti Elettronici S.P.A. Improvements in or relating to telephone circuits, monolithically integrated, for ring trip detection
FR2575021A1 (fr) * 1984-12-18 1986-06-20 Thomson Csf Circuit d'interface d'abonne telephonique incorporant des moyens de detection de decrochage du combine en phase d'appel et procede de detection correspondant
WO1995020289A1 (fr) * 1994-01-21 1995-07-27 Telefonaktiebolaget Lm Ericsson Procede de detection de decrochage pendant la sonnerie d'appel et utilisation d'un circuit d'interface de ligne d'abonne pour detecter le decrochage pendant la sonnerie d'appel
US5734712A (en) * 1994-01-21 1998-03-31 Telefonaktiebolaget Lm Ericsson Method for off-hook detection during ringing and the use of a subscriber line interface circuit for off-hook detection during ringing
CN1080509C (zh) * 1994-01-21 2002-03-06 艾利森电话股份有限公司 一种检测振铃期间摘机状态的方法
EP0675629A1 (fr) * 1994-03-04 1995-10-04 Siemens Aktiengesellschaft Procédé pour la détection sûre de décrochage pendant l'alimentation d'un signal de sonnerie dans une centrale téléphonique numérique et circuit pour sa mise en oeuvre

Also Published As

Publication number Publication date
DK116083A (da) 1983-09-25
BR8301380A (pt) 1983-11-29
CA1194627A (fr) 1985-10-01
ES520573A0 (es) 1984-03-01
IT1155661B (it) 1987-01-28
EP0089687B1 (fr) 1986-11-26
JPS58207758A (ja) 1983-12-03
DE3367993D1 (en) 1987-01-15
EP0089687A3 (en) 1984-12-19
DE89687T1 (de) 1985-05-09
ES8403001A1 (es) 1984-03-01
DK116083D0 (da) 1983-03-10
IT8267371A0 (it) 1982-03-24
US4528425A (en) 1985-07-09

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